Plural of mold; either fungal growths that develop in damp conditions, or hollow forms used to shape materials.
Two separate etymologies: fungal mold from Old French 'modle' meaning soft earth, and shaping mold from Old French 'moule' meaning form or matrix. Both ultimately trace to Latin roots related to measure and form.
Penicillin, one of medicine's greatest discoveries, came from the Penicillium mold that Alexander Fleming noticed had contaminated his bacterial culture. Meanwhile, injection molding revolutionized manufacturing by allowing complex plastic shapes to be mass-produced with incredible precision.
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